Navigational instrument



March 9, 1-954 5 c so 2,671,270

NAVIGATIONAL INSTRUMENT Filed April 19f 1947 INVENTOR.

ATTOR N EY.

Patented Mar. 9, 1954 UNITED STATES PATENT OFFICE NAVIGATIONAL INSTRUMENT Ewell Richardson, Los Angeles, Calif.

Application April 19, 1947, Serial No. 742,502

1 Claim. (Cl. 3 3-1) This invention relates to the design of a terrestrial globe and to attachments for terrestrial globes whereby the great circle track between any two points on the globe, either meridian or non-meridian in nature, may be plotted upon the globe. The device of my invention can be employed for determining the compass direction or the azimuthal bearing of any such great circle in respect to any point on said great circle.

Another object which is accomplished by the device of my invention is to determine the longitude and latitude of any position on any great circle plotted upon such a globe.

Another object which is accomplished by the design of my invention hereinafter described is to determine the angular distance or the distance in miles between any two points upon a great circle.

While the device of my invention is useful as an educational instrument or useful as an attachment to a terrestrial globe however employed, it is particularly useful in navigation either aerial or at sea.

My invention will be further described in connection with the drawing, in which Fig. 1 shows the mounting of the annular circles upon a terrestrial globe according to my invention;

Fig. 2 is a section taken along the line 2-2 of Fig. 1;

Fig. 3 is a section taken along the line 3-3 of Fig. 1;

Fig. 4 shows a specific application of my invention showing how it may be employed.

The globe I may be an ordinary terrestrial globe. Mounted upon the globe is a band 2 which makes a snug but slidable fit with the globe I. The band 2 is curved transversely to give an inner surface 5 having a radius of curvature equal to the radius of curvature of the globe so that the band fits snugly against the surface of the globe, the inner surface 5 fitting the outer surface globe I. The outer surface 5' of the band 2 is concentric with the inner surface 5. The band 2 is thus an annular spherical zone having an inner diameter equal to the diameter of the globe I. A second band 3 is mounted upon the band 2. The inner diameter of the band 3 is equal to the outer diameter of the spherical surface of the annular spherical zone band 2. It is also curved at 8 transversely at a radius of curvature equal to the radius of the outer surface of the band 2 so that the inner surface 8 of the band 3 makes a snug and slidable fit with the outer surface of the band 2. The outer spherical 2 surface of 3 is concentric with the inner surface of 3 and all inner and outer surfaces of the bands 2 and 3 are thus concentric with the globe. Bands 2 and 3 are thus annular spherical zones.

Each of the bands 2 and 3 is preferably made of a transparent material such as one of the transparent plastics, for example, the methyl methacrylate plastics such as are well known and which need not be further described. They are each scribed with a line intersecting the diameter of the annular spherical zones. Thus, band 2 is scribed with the line 6 and band 3 is scribed with the line Ill. The lines are marked in degrees and fractions of a degree, indicating north and south latitude. These lines are thus concentric with equivalent global great circles.

The bands 2 and 3 are rotatably mounted upon the globe by means of a pivot pin 9, the center line 9 of which passes through the north pole of the globe and intersects the bands 2 and 3 at the lines 6 and I0, respectively. They may also be mounted in like fashion by a pin, the center line of which passes through the south pole of the globe and intersects the lines 6 and I 0.

A third annular spherical zone band I2 having an inner diameter equal to the outer diameter of the band 3 is mounted over the band 3. The inner surface of the annular spherical zone band I2, as shown at I3, has a radius of curvature equal to the radius of the outer surface of the annular spherical zone band 3. It is thus of a spherical inner surface concentric with the globe and with the annular spherical sector bands 2 and 3. The inner surface I3 thus makes a snug and sliding fit over the outer surface of 3. The band I2 is scribed with a circle I5 intersecting the diameter of the .annular spherical zone band I2 and is thus concentric with equivalent great circles of the globe I. The circle I5 is marked with angular degrees and fractions of the degrees of east and west longitude.

Mounted on the band I2 is a pivot pin I4 the center line of which intersects the line I5, and rotatably mounted on the pivot pin I4 is a spherical protractor I6 which is concentric with and in contact with the outer surface of band I2 and rotatable about an axis at a point where the center line of I4 intersects the line I5. The protractor may be divided in degrees and also may be provided with compass markings and may be made of a transparent material such as the plas tics previously referred to.

The annular bands may be mounted by splitting the bands and assembling them by opening up the band. When they are mounted in position they may be closed and the ends connected by a suitable plastic cement, as will be understood by those skilled in the plastics art.

The bands 2 and 3 are pivoted at the poles and may be termed meridional bands, since the lines 6 and are coincident with the meridians. The band I2 is movable to all great circle positions on the globe. Thus when the line I is made coincident with any meridian the band I2 is a meridional band and, in fact, line I5 can make a spherical angle with the index line 6 or [0 of the meridional bands, the vertex of which is at the poles and which may be from 0 up to 360 since [2 may be rotated through 360 on H) and I0 may be made coincident with 6.

However, the band [2 may be $116 from such polar positions to a position where the line I5 is at a spherical right angle to either [0 or IS. The band I2 is then an equatorial band.

The band [2 may be adjusted over the face of the globe to various great circle positions between the meridional and the equatorial positions at all acute or obtuse angles to the meridional bands, so that the intersection of the lines 15, .IB, and S will form spherical triangles which may be right spherical triangles. However, these triangles may also be obtuse or acute, including also the polar triangles thereof, with the band 42 in either an equatorial or non-equatorial position.

This is made possible by the fact that the band 12 is a great circle band freely s'lidable over the meridional bands to all great circle positions between the equatorial and the meridional posi tions.

The plotting of a great circle upon the globe i may be attained in the following fashion. Suppose we wish to determine the great circle track between points A and B, the longitude and lati tude of which are known. I may employ a map printed upon the surface of the globe with the usual meridian lines and the usual latitude lines. I may more accurately determine the position by employing the device as follows:

With band 2 set so that line 6 is rcoincident with the meridian of Greenwich, that is, the zero longitude, and with the band i2 set so that line i5 is coincident with the equator, with the zero point of line 15 on line 6, .band .3 is rotated until line intersects at the longitude of B as read on [2. Holding band 3 in the position thus 'determined and with [2 at its equatorial position with the zero position of 4-2 at its previous posi tion on thezero meridian, the annular band .2 .is rotated until the longitude of A is obtained where 6 intersects i5. 1 now have the bands .2 and 3 positioned on the meridians 'of both A and :B. Holding bands 2 and 3 in position, band I2 is moved until the center line of the pin i4 is coincident with line to at the latitude of B as read on line H) and line 15 intersectslin'e 6 at the latitude of A as shown on line 6, I have now established the great circle track between A and B given by line 15.

reading the angular distances between any :two

points as thegreat circle track for the divisions on line IS, the distance betweensuch rtwoipoints is obtainable, as will be understood by those skilled in the art of navigation;

Various modifications f'of the con'struction as as in the construction illustrated tn the drawing because of the interference between the ends of the half bands at the mountings 9. it

The term annular band as employed herein is meant to include such half bands so mounted.

Instead of fitting band l2 over the annular bands 2 and 3 and mounting the protractor on said band, band l2 may be fitted underneath said bands 2 and 3 and in direct contact with the sphere and the protractor may be mounted upon any one of the bands 2 or 3. I prefer, however, to employ the construction as shown in the drawing.

While I have described a particular embodiment of my invention for the purpose of illustration, it should be understood that various modifications and adaptations thereof may be made within the spirit of my invention as set forth in the appended claim.

I claim:

A device for plotting the great circle track between any two points on a globe, comprising an annular spherical zone band having an inner diameter equal to the diameter of the globe, a line scribed on the outer surface of said band intersecting the said outer diameter of said band, latitude degree markings scribed thereon, a sec= ond annular spherical zone band having aninner radius equal to the radius bf the outside surface of the first mentione'd band, a line scribed on the outer surface of said second hand intersecting the outer diameter of said second band, latitude degree markings scribed thereon, a rotatable pivot mounting for said annular spherical zone bands at the poles of said globe, the pivotal axis References Cited in the file of this patent UNITED STATES PATENTS Number Name I Date V 51, 04 Houghton une 12,1901) 780,225 .Pelleh'an an. in, 19105 1,016,17 'Roc'a Jan. 30, 1912 2,055,148 Hagner Sept. 22, 19,36 2,102313 Hall "Dec. 14, 193.7 2,151,601 Johnson Mar. v1, 1939 3,1833 '65 colejman Dec. 19., 19. 39 2,374,7 8 Steele Mayil, is s 2,429,754 triagner o'ct. '28, 1947 2,443,249 'l-Ia'gner June '15, 1948 2,466,225 Gee Apr. 5, 1949 FGREIGN PATENTS Number Cou'ntry Date 3,645 Great Britain i Jail. 30,181? 14,105 I 858 1 16 

